1. Field of the Invention
This invention relates to a novel thrombin-binding substance and a process for producing such substance.
2. Description of the Prior Art
A variety of researches have heretofore been conducted into the role which thrombin plays as a proteolytic enzyme in the control mechanism of blood coagulation, whereby the mechanism of the coagulation system has been substantially fully elucidated. Recently, it has been reported by N. L. Esmon et al that thrombin serves to activate protein C in a living body, which protein C is said to act on the fibrinolysis and anticoagulation mechanisms, and that a factor capable of functioning as a coenzyme for such activation system is present in extracts of rabbit lung tissue [J. Biological Chemistry, 257, 859-864 (1982)].
The present inventors have directed their extensive studies to the role of thrombin in the human coagulation and fibrinolysis mechanisms, especially to the effect of thrombin on the fibrinolysis mechanism. It has now been found that thrombin takes part in the activation of protein C even in human blood vessels and that a factor exists which, when bonded with thrombin, can accelerate the activation of protein C. It has also been found that such factor can be isolated in pure form from human placentae.